The organs of all living beings, including humans, gradually deteriorate with age following birth and growth, their functions eventually stop, and once those portions of organs for which functions have stopped reach a certain point, death occurs. The process by which function gradually deteriorates is referred to as aging. Since the skin is directly subjected to the effects of the surrounding environment, and has an important function for maintaining the environment within the body, although it rarely completely loses its function, it is susceptible to the appearance of signs of aging such as wrinkles, spots, darkening and looseness, and this is particularly prominent at locations of the skin exposed to sunlight.
As aging of the skin progresses, its defense against stimulation such as oxidation stress weakens. This causes a disturbance in the skin's internal environment, which further promotes aging. At exposed portions of the skin in particular, since these locations are continuously exposed to ultraviolet radiation and other forms of strong oxidation stress, the progress of aging is remarkable. This type of change in the skin is referred to as photoaging, and skin affected in this manner demonstrates thickening of the epidermis, and a reduction in collagen which is a major constituent of the dermis. Consequently, an aesthetically displeasing state results such as the formation of deep, large wrinkles.
Although retinoic acid is used as a prescription drug in the United States as a substance having alleviating effects on wrinkles formed as a result of the progression of photoaging, due to strong adverse side effects and problems with safety, it has not been approved in Japan (see non-patent document 1). Thus, there is a need for an antiwrinkle substance having a high degree of safety and adequate effects.
On the other hand, sclareol is a diterpene alcohol represented by the following formula (2), and is obtained from extracts and refined oils such as Salvia sclarea, which is a member of the lamiaceae family of plants which are easily cultivated. Since sclareol has a structure similar to female hormone (estrogen) and has excellent hormone regulatory action, it is applied in aroma therapy and other aroma fields (see non-patent document 2). In addition, although an agent which inhibits melanin production due to sclareol formulated therein have been proposed (see patent document 1), there have not been any studies conducted on its safety during application or on its wrinkles alleviating effects.

Therefore, as a result of extensive studies conducted by the inventors of the present invention, it was clearly determined that sclareol has skin sensitizing properties. Namely, sclareol was found to have problems with safety depending on the amount formulated into skin cosmetic composition.
patent document 1: Japanese Patent Publication No. 3236130
non-patent document 1: Hamada, Y. and Fukuse H.: “Vitamin A and its Derivatives as an Antiwrinkle Material”, Fragrance Journal, Fragrance Journal Publishing Co., Ltd., Apr. 15, 1998, Vol. 26, No. 4, pp. 75-77
non-patent document 2: Itoh, M.: “Application of Lamiaceae Plants to Cosmetics—Focusing Primarily on motherwort”, Fragrance Journal, Fragrance Journal Publishing Co., Ltd., May 15, 2001, Vol. 29, No. 5, pp. 77-80